The method in question serves to produce a casting mold for sand casting and called “mold production process”. The term mold production process represents various methods of producing a casting mold used for producing workpieces from castable materials. In this context, there are different methods differing from one another e.g. insofar as whether the sand mold is produced by hand or by a machine (hand molding, machine molding), whether the sand mold is destroyed during the casting process or is repeatedly usable (lost molds, permanent molds) and whether the models used are disposable models (lost models, investment casting and full-mold casting) or permanent models (hand molding, machine molding, mask molding, vacuum molding) or whether no models are used (continuous casting, die casting, etc.).
At any rate, what is here dealt with is the production of a casting mold that is based on a model of the workpiece to be cast.
For producing such a mold, a molding flask is required, which, like the model, may e.g. be bipartite. Hence, two molding flask halves may be provided. The molding flasks are normally open at the top and at the bottom. The sand used is pourable and has a plastic condition. In classical sand casting processes, the sand is encompassed by or mixed with fine clay or bentonite. The sand-clay mixture is mixed with water. This is referred to as clay-bound or bentonite-bound sand. This moist sand is often also referred to as green sand.
The sand is poured around the model and compacted. After having been compacted, the sand adheres to the inner wall of the flask and defines a negative of the model contour.
The more detailed the model is, the more precisely and carefully the sand must be poured around the model and compacted.
According to the prior art known in practice, compacting is carried out, irrespectively of the model and the contour, via a large head covering the molding flask and comprising compacting cylinders. This has the effect that the sand above the model will be compacted more highly than the sand at the sides of the model, viz. due to the longer distance along which compacting takes place at the sides. In the final analysis, no attention was paid to the effect which the presence of the model in the molding flask has on the compaction of the molding sand around the model. Compacting was carried out unidirectionally without taking into consideration the contour of the model.